*{
    margin: 0;
    padding: 0;
}
ul li{
    list-style-type: none;
    
}
select{
    padding: 8px 12px;
    border-radius: 5px;
}
h1{
    text-align: center;
}
.sousuo{
    padding: 6px 12px;
   
}
.sskuang{
    padding: 6px 12px;
    
}
thead tr td span{
    font-weight: bold
}
thead tr{
    border-bottom: 2px solid slategray; 
    font-weight:bold;
}
table{
    margin-top: 20px;
}